bttrnham



A. M. BURNHAM.

OVEN.

APPLICATION FILED sEPT.I9.1914.

Patented Aug. 8

a SHEETS-SHEET 3.

Invenror. ArThur M. Burnhom b y lm 45 drawings-a selectedembodimentthereof in V storing up heat therein. In the lllustratedARTHUR M. BUB, OF GAIRDII'ZIQ'EB, MAINE.

OVEN.

To all coho m, it may concern:

Be it known that I, Am'rmm M. BunNnAM,

a citizen of'the United States, residing at Gardiner, county ofKennebec, State of Maine, have invented an Improvement in' Ovens, ofwhich the following description, in connection with the accompanyingdraw-V ing, is a'specification, like characters on the drawingrepresenting like parts.

I propose to provide a plurality of heat.-

ingielements, and the controlling device is of such a nature that as thetemperature in the oven increases beyond a predetermined point theheating elements will be successively rendered inoperative, while whenthe temperature begins to drop from its maximum point, the heatingelements will be ren dered successively operative again, this actionbeing automatic so that the temperature can be maintained-at any desiredpoint. I have also provided means whereby when all of the heatingelements "have-been. renvderelsl inoperative, theair inlet opening tothe oven chamber will be closed so. as to prevent the rapid escape ofthe heat therefrom by convection. Further I have provided a thermostaticdevice for controlling the valves which is constructed to eliminate alllost motion-and which, therefore, will be i extremely sensitive andaccurate.

I form -of; adiusting device for the therm0= "static frod; Fig 3 is asection on the line .F ;F s a el elh i m These and other features andobjects of my invention will be more fully hereinafter described and thenovel features of the inv1ention'will be. pointed outinthe appended caims, I

In order to give a proper understanding of my invention, I haveillustrated in the I Figure 1 is a. front view of an oven made" inaccordance with my invention; Fig. 2

'a' partial side view of the oven showing one Specification of LettersPatent.

section through the oven on the line kk, F 1g. 1, showing anotherarrangement of the thermostatic rod. Fig. 4 is a plan view of the fuelsup ly' valves and the controlling device there or; Fig. 5 is a verticalsection view through the oven; Fig. 6 is a detail showing the manner ofoperating theval'yes' for the air inlet opening; Fig. 7 is anenlargedsection on the line y-y, Fig. 8;

- l 'atented Aug. 8, 1916.

Application filed September 19, 1914. Serial No. 862,512.

8 is an end view of the valve controlhngmechanism showing the means forwin g the valve-actuating springs; Fig. 9 is a plan view of the bottomof the burner chamber show ng the air inlet openings; Fig. 10 is avertical sectional view through the burn- 1 crs andbottom of the burnerchamber show ing the manner of controlling the valves for the air inletopenings; Fig. 11 is an enlarged sectlonal view through one of the fuelsupply valves on the line cw, Fig. 4; Fig. 12 is 11; Fig. 13 is asection on the-line c0, Fig. 11; Fig. 14 is a detail of the e'scap'ementdevice of the valve-controlling mechanism; Fig. 15 is a fragmentarysectional view showing the manner of adjusting the oven bottom;'Figs. 16and 17 show other arrangea section on substantially the line bb, Fig. 1

with a solid front Zalso preferably of cast iron and which is hereinshown. as bolted to embodiment of the invention the side and back wallsof the oven are provided with a dead airspace 3-and with a lining 4ofsome heat-conserving material which will readily absorb heat-but willretain the heat thus absorbed. 'Soa'p stoneis a; good material for gthis purpose, but any heat-conserving material may be employed. The deadair space 3 is formed between two sheet-metal walls 5 that are securedto and retained in positionby the legs of said angle iron posts 6 at therear corners of the oven and by the flanges 8 formed on each side of thefront 2 of the oven, as seen in Fig. 3.. The dead air space 3constitutes a heat insulation which pre-. vents the escape of heat byradiation. and the lining 4 of heat-conserving material absorbs andretains the /heat in, the oven and prevents the oven from coolingrapidly" when the heating elements are rendered inoperative. The front 2of the oven is provided with a door opening which is closed by the usualdoor 9.

' While so far as many features "of this inburner chamber 12, the latterhaving some suitable burner 13 therein. The oven bottom 10 willpreferably be made of some heatconserving material such, for instance,as soapstone, and is of such dimensions as to provide a passageway 14forming a communication between the cooking chamber 11 and the burnerchamber 12. The oven is also provided with a discharge passage for theescape of the products of combustion,

such passage being shown at 15 and extending' along overthe top of theoven and down the back side'ofthe oven to the outlet port 16 whichcommunicates with a flue 17 at the back of the oven. The space orpassage 15 willpreferably extend the full widthof the oven andcommunicates with the oven chamber 12 at the top thereof near the front,as shown at 18. With this arrangement the heated air delivered from theheating element 13 will pass through the space 14 into the heatingchamber ,11 and will then pass through the opening18 into the discharge.passage '15 and thence to the flue 17. The passage of 15 keeps the topand back side of the oven heated and thus increases the efliciency ofthe oven. At the outer sideof the passage 15 the oven will preferably beprovided with heat-insulating material 19 which will prevent the loss ofheat by radiation.

The bottom 20 of the burner chamber 12 is provided with one or more airinlet openings 21 through which air is supplied to support combustion.

One feature of my invention relates to a novelthermostatic device forcontrolling the operation of the heating elements in the the hot gasesthrough the passage screw-threaded projection 2 burner chamber 12,whether these heating elements be in the nature of gas burners or be inthe nature of electric heaters. This thermostatic device is in thenature of the usual thermostatic rod or bar which extends transverselythrough the oven and which operates by its expansion and contraction torender the heating elements operative or inoperative. In my improveddevice, however, this thermostatic bar is so mounted and constructedthat all lost motion is eliminated 'and the apparatus is, therefore,made extremely effective and sensitive. Furthermore, the manner ofmounting the thermostatic rod is very simple and inexpensive. As shownin Fig. 3, one end of the thermostatic rod 22 extends through the flange8 of the front 2 and has screw-threaded there ,7

on an adjusting nut 23 which rests against the outside of the flange 8.This adjusting nut is shown as provided with 'gear teeth 24 which meshwith a gear 25 mounted on the stud 26 and'having associatedtherewith anI Said bar 32 has a spring 33 connected thereto which tends normally tomove the bar to the right Figs. 1 and 4. This spring thus keeps the nut23 firmly against the of the front 2 and takes up all lost motion in theconnections. As the thermostatic rod 22 expands or contracts the bar 32will have a movement which, however, is very much greater than theamount of expansion or flange 8 contraction of the rod 22 .owing to therelative lengths of the lever arms of the lever 29. During suchmovementof the bar 32 the spring 33 yields but always keeps the connectionstaut. v

In Figs. 3",316 and 17 I ha've shown other arrangements of thethermostatic member which embody my invention. construction isillustrated by which the .ex-

-pansion of th'e thermostatic rod. is considerably multiplied. Asillustrated in said figure the thermostatic rod 22 is pivotedv at oneend at 241 to a member 240 that extends oven exterior thereto along oneside of the said thermostatic rod and at the other end 22 is pivotallyconnected to another member 243 that extends along the other side of theoven exterior thereto.

75 which extends through a flange 276 formed on the oven front 2 and towhich the adjusting nut The member 240 has extending laterally from itsfront end a 23 is screw-threaded. The rear end of the by the oven andthe front end of the membeg/ 243 is pivotally connected to the lever 2which in turn is connected at its lowered to the bar 32. In thisembodiment of/the. invention thethermostatic rod 22 is located near therear of the oven and theconstruction is such that any expansion orcontractionof the rod 22 is greatly multiplied in the movementof the bar32. Moreover the spring 33 will operate to -ma intain all of theconnections and joints tight and will prevent any lost motion. In Fig.16 I have illustrated a different arrangement for multiplying theexpansive ,movement of the thermostatic member. /In this embodiment oftheinventibn the thermostatic member comprises three elements, 229, 221and 222 which are connected together by a system of levers. The member220 projects through the side of the oven and has the adjusting nut 23screwed thereto. Said .member is connected to one end of a lever 224pivoted at 225, the other .end of said lever being connected to one endof the member 221. This member 221 is also connected to one end of alever 223 at the opposite side of the oven which lever is pivoted-at 226and is also .pivotally connected, to the other therm0- static member222, the .latter extending through the side of the oven and beingpivjoted to the upper end of the lever 29. The

levers 223 and. 224 are illustrated asp'ivotally connected to theflanges 8 of the oven front 2. With this arrangement all three of thethermostatic members 220, 221"and 222 will expand and contract and thetotal movement given to the lever 29 will be the sum of the expansivemovement of the three I members 220, 221 and 222.

In the above described embodiment of the invention both the lever 29 andthe adjusting nut 23 are carried by and have bearing on the oven front2. Under some conditions of use, theoven front may become heated to suchan extent that with this arrangement the expansion thereof will affectthe accuracy of the operation of the device. If

lever 29 being pivotally connected to one arm thereof and the adjustingnut 230 which has" screw-threaded engagement with the thermostatic rod'22 bearing against the other. arm thereof. This supporting frame 151 maybe secured to the oven front 2 but suitably insulated therefrom so thatit will not become heated while the oven islin use.

With such an arrangement any expansionor contraction of the oven front 2Wlll not 1n-.

terfere at all or affect the accuracy of the thermostatic device. V

So far as the operation of the thermostat as thus far described isconcerned the bar 32 might control electric switches for an electricheating element or valves for a gas burner. It is the latterconstruction which I have chosen herein to illustrate and which will nowbe described.

In the preferred embodiment of my invention I employ a plurality ofburners with a valve for e. ch burner, and provide means whereby as t ethermostatic rod 22 expands and the controlling bar 32 has itscorresponding movement, the valves of the burners will, be closedsuccessively, while when the thermostatic rod 22 contracts thecorresponding movementof the bar '32 will operate to cause the valves tobe opened successively. While any number of burners and their valves maybe used, I have ,herein illustrated two burners and two valves therefor.The two burners are shown at 34 and 35, respectively, and they aresupplied with gas from a main supply pipe 36 through two branch pipes'37 and 38, each pipe having a valve (39 and 390) therein, the operationof which is con trolled by the bar 32. The construction of the valvewhich I prefer to use is best seen in Figs. 11, 12 and 13 and itcomprises a stationary valve member 40 provided with two separatedchambers 41. and 42, one constituting an inlet chamber andthe other anoutlet chamber, said chambers being connected with the branch pipes(37*or 38). This valve member 40 is also provided with a valve seat face43 ,having a lurality of ports. therethrough which lea-g into thechambers 41, 42, there being three ports leading into each chamber, theports leading into the inlet chamber 42 being designated 44 and thoseleading into the outlet chamber being designed 4i5. The valve also isprovided with a- .movable valve member 46 formed with a chamber 47 andwith a valve seat face 48 that fits the valve seat face 43, the latterhaving a plurality of ports 49 therein adapted to register with theports 44, 45 when the valve member 46 is in proper position. The valvemember 46 is rotatively mounted on the valve member 40,

this being herein accomplished by providing the movable valve. member46,with a stem 50 which extends through the valve member 40 and ismountedto turn therein. The valve faces 48 and 43 are yieldingly heldinengagement by means of a spring 7 52 which encircles the stem 50 andengages the valve member 40 at one end and at the other end engagesacollar'51' on the stem 50.

iso

These teeth co6pe'rate with the bar 32 to There will preferably be sixports 49' in the valve member 46 so arranged that when the valve memberis in the position shown in Fig. 12 said ports 49 register with both theports 44 and 45,and when this condition exists there will be a freepassage of gas from the mechanisms are similar a description of one willsuffice for both. Under normal conditions the valve will be opened andthe valveactuating spring will be held from operation by the bar 32until the temperature in the oven reaches a predetermined point, at

which time the'bar 32 has been moved into a position to release thespring and allow it to act to close the valve. There is a spring foractuating each valve, said springs being shown at 53. These springs areherein illustrated as coiled springs which .are mounted on a ,rod orsupport 54, one end of each rod being journaled in a bearing 55 risingfrom the base 1 and the other end being connected to the valve member46. One end of the spring 53 is connected to the, rod 54 so that thetendency of the. spring to unwind tends to turn the rod 54 and thus toturn the valve member 46. Means are'provided for winding up the springfrom the other end, as will be pres-' ently described. Each rod 54 hasfast thereto a toothed disk "56, the successive teeth'57 of which areout of line with each other.

control the operation of the valve. The bar -32 is provided with a'notch 58 of a size to admit the passage therethrough-of the teeth 57,and under'normal conditions this notch is so positioned as to be outof'line with the teeth so that one of the teeth 57 will engage the bar32-and thus hold the spring 53 from unwinding.

When the bar32 moves into a position to 1 'bring the notch 58 oppositethe tooth which rests on the bar, then the expansive move- 7 ment of thesprin will carry said tooth throughthe notch, thus allowing the valve to60 be given a partial turning movement. This turning movement isarrested, however, by the next tooth- 57 which being v out 'of line withthe first-named tooth will be out of line with the notch and will,therefore, be G6 brought up agalns tthe bar 32. The teeth valve will bealternately opened and closed.

32. Inasmuch as the two valve-operating 57 are spaced apart an angulardistance equal to half the angular distance between the ports in thevalve member 40, so that, assuming that the valve is open, the firstforward movement of the disk and valve member 46 will close the yalve,while the next forward. movement will bring the ports into alinementagain, thus opening the valve. .With'this construction, therefore, thevalve will be'alternately opened and closed as the valve member rotates.This valve construction is one in which the valve member 46 is designedto rotate continuously in the same direction and during such rotationthe The construction of the parts is such that y when the oven is" notheated the notch 58 will be at the left-hand side of the disk 56. As

the ovenbecomes heated and the thermostatic rod expands the bar 32 willmove to the right Fig. 4, and when the notch 58 comes inalinementwiththe tooth which engages the bar, thenthe valve member willmove forward one step until the next tooth brings up against the bar.This step forward will close the valve andwhen the'oven .cools and thethermostatic rod contracts the movement of the bar '32 in the opposite'\direction will again bring the notch into 'linement with the tooth whichrests thereagainst, thus allowing the valve to have. another step for-.ward thereby to open it again{ This disk 56 and the bar "32 thus form asort of escapement device which operates to effect an al-. ternateopening and closing of the valve as the thermostatm bar expands orcontracts.

As stated above, the bar 32 is designed to control both valves 3% and390 and I will preferably so arrange the parts that these valves will"be operated successively rather than simultaneously. This'isaccomplished by so arrangingthe valves 39 and 390 that temperature inthe oven remains at substantially the same po nt, then the valve 39 willremain open. I propose to make the two burners 34 and 35 of differentsizes. The

burner which is supplied by the valve 39 will preferably be somewhatsmaller than the other burner. The advantage of this construction isthat'when'the oven reaches 125 a predetermined temperature and the valveI 390 becomesclosed, the smaller' burner sup-1 plied from'the valve 39'will presumably furnlsh just about enough heat to hold the temperaturelnthe oven. If, however, the" in for it will be readily observed thatsince the 'nut 23 bears against theside of the even any turning movementthereof will shift the 'sponding valve member 46.

closed, If both valves have'been closed, then when the temperature inthe oven decreases ,the valves will be successively opened, the valve 39being opened first. The temperature at whichthe valvev 390 will beclosed can be determined by adjusting the indicator,

thermostatic "rod 22 logitudinally and thus shift the position of thebar 32 relative to the disks '56. The numbers on the indicating disk 27will be so arranged that the number 'which is visible through the sightopening 28 will indicate the temperature at which the valve 390 will beclosed.

In order to prevent any binding of the parts I propose to provide aflexible coupling between each rod 54 and the corre- As herein shown,each valve; member is providedwith pins 60 extending therefrom whichloosely engage apertures or'notches formed in the head 61 mounted on theend of the shaft 54 so that turning movementof the shaft will becommunicated to the valve'member, but

'the parts will not bind even though, said valve member and shaft 54 arenot axially in alinement.

tion bywh'ich, when the valve 390 is closed the air mlet openings 21will; be partially closed'and when the valve 39 is closedsaid air-inletopenings will be completely closed.

Asshown, in Fig. 10 there are two air inlet ports or openings 21fandgavalve-62 is provided for closing each port. Said valves are carried byarms that are pivoted to the bottom 20 at 63 and the arms extend be yondthe pivot points 63 as'shown at 64, said extensions 64 overlapping eachother and one extension carrying a rod or pin that operates in aslot inthe other extension. The

in unison.

with two cam'members 69 i 690, respecttively, by whichthe operatlon-ofthe valves i F i v 62 are eontrolled. Cain member 69 is fast on theshaft 54 controlling the valve 39 and the cam member 690 is fast on the'shaft 54' controlling the valve 390 and the construction is such thatwhen the valve 390 is closed the cam member 690 will allow the valves 62to become partially clos'ed while when the valve'39 is closed the cammember 69 will allow the valves ,62 to become completelyclosing movementof the. valves is secured bysome automatically operative means such asthe spring 72, which is connected to the arm 67;. Each cam member 69and'690 is pro-.

.vided with aseries of rises 70 and depressions 71, there being the samenumber of rises and depressions on each member as there are teeth on'thedisk 56 for the two valves. The rises 70 on the cam member 690 arehigher than those on the cam 69 and the depressions 71 on the cam member690 are deeper than those onthe cam member 69. When both valves are openthe cam members 69 and 690- are in the relative positions shown-in Fig.'18 and one of the rises or projections 70 on the cam 690 will be inengagement with the arm 302, thus holding said arin depressed againstthe actionof the spring 72 and holding the valves 62 open. The relativedimensions of the rises 70 on the two cam members 690 and 69 aresuchthat when the cam member 690 is in the position shown in Fig. 18, thearm 301 willbe separated somewhat from the adjacent rises 70 on the cammember 69. -Whenever the valve 390 is closed-as above described,

the'cam member 690" will be given one forward step therebyv to carry'the rise' 70 out of engagement with the arm 302 and allowing said arm tomove upwardly through the action of the spring 72." Such upward.movement ,ofthe arm is however arrested by the. arnf 301 coming intoengagement with the cam member 69 and the :parts are held in' thisintermediate position so long as the valve 39 remains open. This partialmovement of'the rockshaft 68 and arm 67 is .per-' I mitted when the cammember 690 is moved forward, one stepbeingsufiicient to part ally,

close the valve 62 thereby reducing the amount of air which can passthrough the air inlet openings. When the valve 39 is closed and the cammember 69 moved forward onestep, then the spring 72 acts to completelyclose the valves 62 as will be r,

obvious. The partsare so arranged that when the valves 62 are partiallyclosed as occurs after theva'lve 390 has been closed, the amount ofair-. iw'hich willvbe admitted through the inletopenings 21 is justsufi- 'cient to support icon'ibustion (if the burner' I still remainingin operatlon. By this ar- "rangement, whereb the valves 62 afe closedprogressively as the burners are shut off, I prevent the possibilitywhen only one burner is lighted of a current of air of sufiicientvolume'passing through the oven to cool the I provide means whereby theshutoff, then the passage throughthe oven chamber 11 is closed so as toprevent ,the escape of heat-by convection.

I have also provided means for automatically winding the springs 53which means are herein shown as operated by the oven door 9, theconstruction being such that the opening and closing movement of theoven door 9 acts to wind the springs. The construction is also of such anature that the opening movement of the door will-wind one spring whilethe closing movement will wind the other, b t this particulararrangement is not essen ial. to the invention. Each spring 53 isanchored at one end to a.disk 73 loosely mounted on the shaft 54 .andhaving frictional engagement with a gear m mber 74 also'loosely mountedon the sh ft. These two members 73 and 74 are held in frictionalengagement by a spring washer 75, thus making a frictional clutchbetween them. The gear 74 meshes with a rack 76 which is slidablymounted in suitable guides and is connected by means of a link 77 with acrank arm 78 formed on the pivot shaft 7 9 of the oven door 9. Themember 73 is in the form of a ratchet, it having ratchet teeth thereonwhich are engaged by a pawl 80 to prevent rotation thereof in onedirection. With this construction it will be seen thatthe movement ofthe rack bar 7 6 will rotate the gear 74, and when the gear 74 rotatesin one direction the friction member 73 will befldriven forwardly by itthere by winding up the spring 53, while when the gear member 74 rotatesin the other direction, due to the reverse movement of the rack gearfrom rearward movement by the pawl 80, the friction. connectionbetweenth members 73. 74 permitting a slipping mov ment between them.The two springs 53 are wound in opposite directions and the pawls 80 forthe two ratchet membersgare oppositely disposed, as seen in 8, so thatthe movement of the rack bar 6 in one direction will wind up one spring,the friction connection for the other spring yielding or giving at thistime, while the movement of the rack bar in the opposite direction willwind said other spring, the friction connection for the first-namedspring yielding or giving during this operation.

76, the member 73 will be locked.

It will thus be seen that the/opening and closing movement of the ovendoor 9 is utilized to keep the springs 53 wound.

It will be I will use suitable pilot burners in the oven for lightingthe main burners as the valves 39 and 390 are opened, but I have notshown such pilot burners .herein as they do not form anypart of mypresent invention. 7

I will preferably make the oven bottom 10 adustable vertically. One wayof accomplishing this is shown in Fig. 15 wherein the sides of the ovenare provided with teeth 92 and the oven bottom 10 is provided withplates 93, 94 at opposite edges whichengage and rest on justable and ;isheld in adjusted position by a screw 95 operating througha slot 96 inthe plate v 94. 'When the screw 95 is loosened and the plate 94 movedbackwardly the oven bottom can be adjusted to any desired height, afterwhich it may be locked in its adjusted position by tightening up thescrew 95.

While I have herein illustrated the invention as it might be embodied inan oven 4 adapted to use gas as fuel, yet I desire to understood, ofcourse, that I the teeth. The plate 94 is adstate that the invention isequally applicable to ovens heated by other fuel than gas, such forinstance as gasolene, kerosene, etc., and as above stated many featuresof the 1nven-.

tion are also applicable to an oven whichis heated by electricity. to belimited to any particular character of heating element. Furthermore,although I have illustrated herein a selected embodiment of myinvention, yet I do not'wish to be limited to the constructionalfeatures shown. I claim: 1 In an ven, the combination with an ovenchamber, of a plurality of burners for heating said chamber ,-a fuelsupply valve for each burner, "automatically-operativevalve-actuatingdevices normally held. in-

operative, and automatic means to release said devices successively whenthe temperature in the chamber increases beyond a predetermined pointwhereby the valves will be closed in succession.

2. Inan oven, the

valves successively as the temperature decreases.

- 3. In an Hence I do not wishthe operation of to effect thecloscombination with an 1 oven chamber, of a plurality of. burners foroven, the combination with an oven. chamber, of a plurality of burnersfor v heating the oven, a fuel supply valve for each burner, a motordevice for closing each valve, and thermostatic means torender saiddevlces operatlve to close one valve whenv the temperature 'in the Ovenreaches a predetermined point'and to close another valve when thetemperature reaches a higher point. v

4. In an oven, the combination with an oven chamber, of a plurality ofburners for heating the even, a fuel supply valve for each burner, amotor device'for operating each valve, and therniostatic means to rendersaid devices operative successively to close first one valve and thenanother when the temperature'in the oven increases beyond a predetermined point and to open first one valve and then another when thetemperature deopenings through which air is supplied ,to

support-combustion, a fuel supply valve for each burner, automatic meansto close the valves successivelyasthe temperature in said chamber risesabove a predetermined amount and to open said valves successively.

when thetemperaturedecreases and means to close said air-inletopeningswhen allof the valves are c osed and to open said openings whenone of the valves is open.

7. In an oven, the combination with an oven chamber having a door, of a'burner for heating. the oven, a fuel supply valve for.

said burner, automatically-operative valveactuating means to close said'valve' when the temperature rises above a predetermined point, and toopen said valve when the temperature falls below said point, and meansoperated by the opening and closing movement of the door to store upenergy in said automatically-operativemeans.

8.- In an oven, the combination with an oven chamber having a door, of aburner for heating said chamber, a fuel supply valve for said burner, athermostatically-controlled valve-aetuating spring'for operating thevalve, and means operated by the opening and closing movement of thedoor to store up energy in'said spring.

9. In anoven, the .comblnation with an oven chamber having a door, twoburners "for heating the oven, a fuel supply'valve for I each burner, a-thermostatically-controlled spring for actuating each valve and meansing the same, two fuel supply valves, each operated by theopeningmovement of the door to store up energy in one spring and by the closingmovement of the door to store up-energy in the other spring.

10. In an oven, the combination with an oven chamber, of two valvesfor'heatingsaid oven, a valve-actuating spring for each valve,thermostatic means to control the oporation 0f the valves, aspring-winding element actuated by the opening and closing .movement ofthe oven; door, and means whereby said elerdent winds one spring whenthe door is open and the other spring when the door is closed.

11. In an oven the combination with an oven chamber havinga door, of aburner I element, two fuel supply valves to supply fuel thereto, aspring for actuatlng eachvalve, thermostatic means to control theoperation of each-valve, a rack bar connected to the door to bereciprocated as the door is opened and closed, gears meshing with therack bar and connections between said gearsand said springs whereby onegear operates to wind up'one'spring when the door is opened and theother gear operates to wind up the other spring when the door is closed]12. In an oven, the combination with an oven chamber, of a burnerelement for heathaving a rotary valve member capable of rotationcontinuously in one direction and which opens and closes the valvessuccessively as it rotates means tending normally to rotate each va vemember, and a thermostatically-controlled member controlling theoperation of both valves.

13. In an oven, the combination with an oven chamber, of a burnerelement for heating said chamber, two valves each having a rotary valvemember capable of rotat on continuously in one direction and which opensand closes the valves successively as it v rotates, means tending torotate each valve member, and a thermostatically-controlledvalve-controlling member. normally restraining the operation of bothvalves but adapted to permit. their operation successively as itismoved. 14. In an oven, the comb1nat1onw1th an oven chamber having adoor, a burner element for heating said chamber, two fuel supply valves,each hav ng a rotary valve member capable of rotation continuously 1nonedirection and which opens and closes the valve successively as itrotates, a spring tending to-rotate each valve member, a thermostaticdevice to control the operation of the valves and means operated by theopening and closing movement ofthe 'door to wind said springs. H

.15. In an oven the COIIlblDfitlOILWltll an oven chamber having a door,of a burner, a

'fuel supply valve having a-rotary valve #m'ember capable of rotationcontinuously in to operate the valve,

' ber journaled in the stationary member and contact,

- means one direction and which opens and closes the valve successivelyas it rotates, a 'sprlng er, a thermostatic device to control theoperation tending to rotate said valve memb of th valve and meansoperated by the opening and closing movement of the door 'to wind upsaid spring.

the combination with an In an oven,

a fuel oven chamber, of a burner therefor,

s u'pply valve, automatically-operative means and controlling theoperation of the valveactuating means and a spring connected to saidmember.

17. In an oven, the combination with an oven chamber, of a burnertherefor, a fuel supply valve, automatically-operative means athermostatic rod extending through the oven, an anchoring nut screwed tosaid red by which the latter may be adjusted, a lever connected to therod, a controlling member connected to the lever and controlling theoperation of the valveactuating means'and a spring acting on saidmember. I

18. .In an oven, the combination with an oven chamber, of a thermostaticrod extending therethrough, an anchoring nut screw threaded to said rod,a fuel supply valve, a valve-controlling member connected to said rod, aspring acting on said member, said anchoring nut having gear teeth andan in- 'di'cating member geared to said nut and by Which the adjustmentthereof may be indicated.

' 19. In an oven, the combination with an oven chamber, of a burnertherefor, a fuel supply valve'comprising a stationary member having twochambers constituting inlet and outlet chambers respectively, a rotaryvalvb member having ports, thermostaticallycontrolled means to effect anintermittent rotary movement of said valve member, the

ports therein operating to establish and interrupt communication betweensaid chambers successively during such intermittent movement.

20. In an oven, the combination with an oven chamber, of a burnertherefor, a fuel supply valve comprising a stationary member providedwith an inlet and an outlet chamber respectively and a ported. valveface, a rotary valve member having a champrovided with a ported valveface which engages that of the stationary member,

yielding means to hold the valve faces in and thermostaticallycontrolledtogive the valve member an intermittentrotary movement. '2 1'.-In anoven,the combination with an oven i'chambenp-of a plurality of. heatingelements therefor, a controller for each heating element, anautomat'rpally-operative detroller, and a thermostatically-controlledmember normallylocking said automatically-. 7

operative device from operation but adapted in one position to releaseone of said devices and in another position to release the other of saiddevices.

22. In an oven, the combination with an oven chamber, of a heatingelement to heat the latter, a device to control the heating element andrender the same operative and inoperative alternately, -a spring toactuate said device, a toothed member associated with 30 said device,the successive teeth of which are out of line with each other, a notchedcontrolling bar engaging said toothed member, and a thermostatic memberconnected to said bar for actuating the same, whereby the 35 heatingelement is rendered inoperative or operative as the temperature in theoven chamber rises, and falls. 23. In-an oven, thecombination with anoven chamber, of a heating element therefor,

a spring-actuated device to render said heating element operative orinoperative, a member to control the operation of said springactuateddevice, a thermostatic rod in said chamber anchored at one end,connections 5 between said rod and said member, and a spring associatedwith said connections to take up lost motion. 1 i 24. In an oven, thecombination with-an oven chamber, of heating said chamber, an air inletopening supplied to support combustion, a fuel supply valve for eachburner, thermostaticallycontrolled means sively as the temperature insaid chamber rises' above the predetermined point and said chamberhaving means toclose the air inlet opening progressively as the valvesare closed.

25. In an oven the combination oven chamber, of a plurality of burnersfor heating said chamber, said chamber having an air inlet openingthrough which air is supplied to support combustion, a fuel sup plyvalve for each burner, automatic means 115 to close the valvesuccessively as the "temperature in said chamber rises above thepredetermined point and means controlled by the valve-actuatingmechanism to close theair inlet opening progressively as the valves 12are closed.

26. In an oven the combination with an oven chamber, of two burnerstherefor, said chamber having an air inlet opening, afuel supply valvefor each cally controlled means to close the valvesa successively as thetemperature in said chamber rises above a predetermined amount andmeansfassoclated with the valve-actuating mean'stopartially close theair inlet opening 13 vice tending constantly to actuate each conaplurality'of burners for through which air is to close the valve.succeswith an burner, thermostati- 12 when the first valve is closed andto completely close said opening when the other valve is closed.

27. In an oven the combination with an oven chamber, of a plurality of.burners therefor, said chamber having an air inlet opening, a fuelsupply valve for each burner, automatic means to close the valve succes'sively as the temperature in said chamber rises above a predeterminedamount and to open said valves successively when the temperaturedecreases, and means to close the air inlet opening progressively as thevalves are closed successively and to open said opening progressively asthe valves are opened successively,

28. In an oven the combination with an oven chamber, of two burnerstherefor, said chamber having an air inlet opening, a fuelsupply valvefor each burner, automatic means to close the valves successively as thetemperature in said chamber rises above a predetermined amount and meansassociated with the valve-actuating means to partially close the airinlet opening when the first valve is closed and to completely closesaid opening when the other valve is closed, a d

to partially open said air inlet opening wh n the first valve is openedand completely 7 open said opened;

29. In an oven, the combination with an oven chamber, of a series ofburners for heating said chamber, a series of fuel supply valves forsaid burners, a motor device for operating 'each valve, and thermostaticmeans for controlling andcausing said motor devices to operatesuccessively as the temperature in the oven varies.

30. In an oven, the combination with an oven chamber, of a heatingelement therefor, a controller for said heating element,automatically-operative means tending to actuate the controller, a barnormally locking said means from operation but adapted in opening whenthe second valve is one position to release said means, and athermostatic device to control the position of said bar.

In testimony whereof, I have signed my name to this specification, inthe'presence of two subscribing witnesses.

ARTHUR M. BURNHAM.

Witnesses:

LOUIS C. SMITH, THOMAS J. DRUMMOND,

